A food chain is a linear network of links in a food web starting from producer organisms (such as grass or trees which use radiation from the sun to make their food) and ending at apex predator species (like grizzly bears or killer whales), detrivores (like earthworms or woodlice), or decomposer species (such as fungi or bacteria).

A food chain also shows how the organisms are related with each other by the food they eat.

Note :

Each level of a food chain represents a different trophic level.

Concept of Food chain :

A food chain differs from a food web, because the complex network of different animals’ feeding relations are aggregated and the chain only follows a direct, linear pathway of one animal at a time.

A common metric used to quantify food web trophic structure is food chain length. In its simplest form, the length of a chain is the number of links between a trophic consumer and the base of the web and the mean chain length of an entire web is the arithmetic average of the lengths of all chains in a food web.

Food chains were first introduced by the African-Arab scientist and philosopher Al-Jahiz in the 9th century and later popularized in a book published in 1927 by Charles Elton, which also introduced the food web concept.

Food chain’s length

The food chain’s length is a continuous variable that provides a measure of the passage of energy and an index of ecological structure that increases in value counting progressively through the linkages in a linear fashion from the lowest to the highest trophic (feeding) levels.

Food chains are often used in ecological modeling (such as a three species food chain). They are simplified abstractions of real food webs, but complex in their dynamics and mathematical implications.

Ecologists have formulated and tested hypotheses regarding the nature of ecological patterns associated with food chain length, such as increasing length increasing with ecosystem size, reduction of energy at each successive level, or the proposition that long food chain lengths are unstable.

Food chain studies have an important role in eco-toxicology studies tracing the pathways and biomagnification of environmental contaminants.

Food chains vary in length from three to six or more levels. A food chain consisting of a flower, a frog, a snake and an owl consists of four levels; whereas a food chain consisting of grass, a grasshopper, a rat, a snake and finally a hawk consists of five levels. Producers, such as plants, are organisms that utilize solar or chemical energy to synthesize starch. All food chains must start with a producer. In the deep sea, food chains centered around hydrothermal vents and cold seeps exist in the absence of sunlight.

Chemosynthetic bacteria and archaea use hydrogen sulfide and methane from hydrothermal vents and cold seeps as an energy source (just as plants use sunlight) to produce carbohydrates; they form the base of the food chain. Consumers are organisms that eat other organisms. All organisms in a food chain, except the first organism, are consumers.

Flow of Food Chain:

In Food chain, Organisms that can make their own food are called producers.

Consumers are animals that eat producers or other animals. The animal that eats the producer is called the primary consumer.

The animal that eats the primary consumer is called a secondary consumer. The animal that eats the secondary consumer is called a third order consumer and so on to fourth, fifth, etc.

Also, a food chain represents a series of events in which food and energy are transferred from one organism in an ecosystem to another.

Food chains show how energy is passed from the sun to producers, from producers to consumers, and from consumers to decomposers. They also show how animals depend on other organisms for food.

In any ecosystem, many food chains overlap. Different food chains may include some of the same organisms. Several consumers may eat the same kind of plant or animal for food.

When this happens, the food chain forms a food web. A food web shows how food chains are related within an ecosystem.

Hello Sweta,
Energy Interactions from one trophic level to another happens via Energy transfer or heat loss in metabolic processes.The majority of heat is lost in metabolic activity and only small amount is transferred from one level to another.Many books quote that around 10% of the energy at any trophic level is transferred to the next level.